add swift flatbuffers

flatbuffers/Documentation.docc/Tutorials/reading_bytebuffer.tutorial

@@ -0,0 +1,27 @@
+@Tutorial(time: 2) {
+  @Intro(title: "Reading ByteBuffers") {
+    After getting our ByteBuffer created, we can now read it.
+    }
+    
+    @Section(title: "Reading your first buffer") {
+      @ContentAndMedia {}
+      @Steps {
+        @Step {
+          After fetching the data from disk or network you need to access that data, and that can be done.
+          By simply calling `getCheckedRoot`, which checks if the data is valid before enabling you to read from a corrupt buffer.
+          however, if you are sure that the data is 100% correct you can simply call `getRoot`
+          @Code(name: "ViewController.swift", file: "swift_code_11.swift")
+        }
+        @Step {
+          Now since we have a Monster object, all the fields can be accessed by simply fetching the data. Note, Deprecated fields will not
+          show up
+          @Code(name: "ViewController.swift", file: "swift_code_12.swift")
+        }
+        @Step {
+          And you can access union types as easy as this
+          @Code(name: "ViewController.swift", file: "swift_code_13.swift")
+        }
+      }
+    }
+  }
+